1. Field of the Invention
The present invention relates to a fiber misconnection detecting method and device, and in particular to a method and device for detecting an error of a fiber connection between SONET (Synchronous Optical NETwork) devices.
2. Description of the Related Art
In a network formed of a plurality of SONET devices (hereinafter, referred to as nodes), as shown in FIG. 19, nodes N are connected with fibers (optical fibers) F. Regarding each node N within the network, the node has a plurality of interface slots and one or more adjoining nodes connected with fibers.
Upon network construction, whether or not the fiber connection between the interfaces of nodes N is correct is confirmed. For this purpose, a user on a source (transmitting) side sets a unique J0 byte to be transmitted per fiber (per interface of node) connecting the nodes, and a user on a destination (receiving) side manually sets an expected value for the J0 byte and confirms if the J0 byte received is consistent with the expected value, thereby verifying the normality of the fiber connection between opposed nodes (interfaces).
This will now be specifically described referring to FIGS. 20 and 21.
Firstly, when nodes N#1 and N#2 are connected with an optical fiber, a Section Trace function by the J0 byte of a section overhead is used for confirming if the connection is correct (not misconnection).
In the example of FIG. 20, the source node N#1 sets “AAA” in the J0 byte to be transmitted from an interface IF#3. In an interface IF#10 of the destination node N#2, a user manually presets an expected value “AAA” received from a correct source. In this occasion, the J0 byte actually received by the interface IF#10 of the destination node N#2 is consistent with the expected value, so that it is determined that the connection between the interfaces IF#3 and IF#10 is correct. As for the reverse direction from the node N#2 to the node N#1, it is determined by using another expected value “BBB” that the connection is correct.
While the receiving (reception) expected value of the interface IF#3 of the node N#1 is “BBB” in the example of FIG. 21, the J0 byte actually received from the node N#2 is a value “YYY” transmitted from the interface IF#2 of the node N#2. Therefore, both values are not consistent with each other, so that it is determined that the fiber connection between the interfaces IF#3 and IF#10 is incorrect. Similarly, it is determined that the connection between the interfaces IF#4 and IF#20 is incorrect.
It is to be noted that there has been a method of automatically collecting connection states between nodes (which nodes are connected with each other) by using Link Connectivity Verification of an LMP (Link Management Protocol) which is one of GMPLS (Generalized Multi-Protocol Label Switching) protocol groups (see e.g. non-patent document 1).
Also, there has been a line corresponding information coincident method of an ADPCM transcoder. In the line corresponding information coincident method which makes line corresponding information indicating a line correspondence of signals in opposed devices coincident by the ADPCM transcoder which performs a mutual code conversion between two primary group signals which can accommodate 24 lines of PCM signal whose transmission speed is 64 kbps and a single primary group signal which can accommodate 48 lines of ADPCM signals whose transmission speed is 32 kbps, a line corresponding table indicating a line correspondence of the signals is prepared in the ADPCM transcoder, an address number of the line corresponding table is inserted into the line transmitting signaling information in the primary group signal which can accommodate 48 lines of the ADPCM signal, and the line corresponding information is made coincident by transmitting/receiving the address number between the opposed devices (see e.g. patent document 1).    [Non-patent document 1] RFC4204:LMP RFC4207:SONET/SDH Encoding for LMP Test Message    [Patent document 1] Japanese Patent Application Laid-open No. 62-227240
In the examples shown in FIGS. 20 and 21, the connection normality can not be confirmed unless a user correctly sets the J0 byte transmission value on the source side and the J0 byte receiving expected value on the destination side for all of the slots or ports (interfaces).
Even if the connection normality is confirmed, it is impossible to collect information as to which interface each node is correctly connected to.
Furthermore, when the J0 byte transmission value or the J0 byte receiving expected value is set in error, it is disadvantageous that the fiber connection is recognized as being incorrect even if the actual fiber connection is correct, or conversely the connection is recognized as being correct even if a misconnection occurs.
Also, in case of the non-patent document 1, numerous messages are transferred by using an IP layer until Verification is completed. Therefore, it is disadvantageous that it takes time until the collection of connection state information of all of the slots or ports is completed. As a matter of course, if either one of the nodes does not support GMPLS, this function can not be achieved.